Breast carcinoma is the second leading cause of cancer-related death in women of the western world. In the United States alone over 175,000 new cases are diagnosed annually. The natural history of breast cancer involves a sequential progression through defined clinical and pathologic stages starting with initially benign then atypical hyperproliferation, progressing into in situ then invasive carcinomas, and culminating in metastatic disease. Ductal carcinoma in situ (DCIS) is the precursor of invasive ductal carcinoma.